We’ve come a long way since tissue biopsies were considered the go-to way to obtain samples needed to test for cancer. Breast cancer, prostate cancer, and lung cancer all required invasive methods to obtain tissue.

Thankfully, liquid biopsies–whether through samples of saliva, urine, stool, or, in Micronoma’s case, blood–provide a much less invasive way than tissue biopsies to obtain material that can be used to test for the presence or absence of cancer.

But not all liquid biopsies are created equal. Each has their own set of pluses and minuses, ranging from how easy they are to collect to how effective each is for diagnosing the cancer a clinician is looking for.

Let’s look at some of the benefits and drawbacks of various liquid biopsy options. And, why Micronoma landed on using a simple blood draw to derive plasma that is then run through our Oncobiota™ platform to identify microbial signals that indicate the likelihood a patient has lung cancer.

And don’t forget, while we’re focusing first on detecting lung cancer with our OncobiotaLUNGdetect  tool, we’ve discovered microbial signatures are present in numerous kinds of cancer that future versions of the platform will be able to detect. See a previous blog on this topic.

A big benefit that saliva, urine, and stool samples all share is that they are non-invasive and easier to obtain. No needles needed. Though, let’s be honest, some of those samples are a little less pleasant to give or collect. Some may call it the “yuck!” factor.

All joking aside though, a big drawback to those kinds of samples is that they offer limited windows through which to look for particular cancers.

A saliva sample might be a promising place to look for disease in the head or neck areas. Urine samples can be effective for identifying things like bladder or kidney disease. But neither are likely to be able to help you spot lung or breast cancer. Lung cancer and breast cancer are in very distant compartments of the body. Saliva, urine, and stool samples just aren’t going to likely provide enough material from the cancer tissue to be effective for that kind of detection, even less so for the kind of early diagnosis Micronoma is offering.

Blood, on the other hand, is circulated throughout the entire body, exposed to all of your organs at some point, providing a much better swath of signals to examine.

Our technology uses plasma derived from a simple blood draw. While that method isn’t non-invasive, it is way less invasive than tissue biopsy methods and we’ve found it provides the necessary amount of material to detect cancer in its earliest stages.

Even though it requires a technician to complete, a blood draw is a much easier way to obtain the amount of blood we need to generate enough plasma (500 ul) to test. In addition, blood draws provide a more consistent picture of the microbiome that can be generalized at population scale more easily than results from saliva, urine, and stool samples, which can be subject to numerous variables–like a patient’s diet, hygiene, sport activities, etc. It’s clear to us that the quick, slight discomfort a patient has to deal with to undergo a blood draw is more than offset by the improved results that a blood sample provides compared to those other biopsy methods.

There’s also talk that a breath biopsy could be used to detect lung cancer, for example. Think of a process similar to a breathalyzer test, except instead of blood-alcohol content you’re looking for metabolites indicating cancer.

While an appealing concept, we’re also concerned with its practicality. While certainly easy to collect, it’s unclear a person’s breath could provide enough specific material to determine if there is cancer and which one it would be. At this point, the idea could be a little bit more sci-fi wishful thinking than close term reality.

So it remains that using plasma derived from a blood draw provides the most complete, generalizable way to identify signals that indicate cancer, and in the case of Micronoma, enough microbial signal for our microbiome-driven liquid biopsy.